Method for obtaining a fibrous preparation for immersion-resistant opaque paper

ABSTRACT

A method for obtaining a fibrous preparation for manufacturing a paper having significant water repellency and opacity in the dry or wet state. Fibres are suspended in water; calcium salts are added to the fibres; a source of carbonate salts in the form of an aqueous solution are added and the resulting mixture is stirred for a time sufficient to allow calcium carbonate particles to be precipitated. A solution of fatty acid salts heated to a temperature which corresponds to the micellisation temperature of said fatty acid salts is added and takes into account the critical micellar concentration of the fatty acid salts. The mixture is stirred thus obtained for a time sufficient to allow the fatty acids to be absorbed at the surface of the calcium carbonate particles and to obtain the desired fibrous preparation.

FIELD

The present invention is situated in the field of obtaining a fibrous preparation for manufacturing a paper having significant water repellency and opacity in the dry or wet state in order to be capable of being affixed, for example, to a wine or spirit bottle capable by the nature thereof of being stored in a wet environment such as, for example, a refrigerator or an ice bucket.

BACKGROUND

In this specific technical field, the prior art includes French patent application FR 3 071 517 filed on behalf of the Applicant and disclosing an immersion-resistant opaque paper for manufacturing labels intended mainly for wine or spirit bottles, remarkable in that it consists of a uncoated base paper substrate composed of fibres and opacifying mineral fillers, said base paper substrate receiving on the front and back faces thereof a surface treatment consisting of mineral or other pigments, associated with water-soluble and synthetic binders.

This paper for labels, while being of interest since, with the surface treatments, layers are obtained limiting the propagation of moisture towards the paper, has a certain number of drawbacks.

Indeed, the opacity and dry and wet environment resistance features of this paper, which are only obtained with surface treatments, are therefore limited and do not make it possible to envisage other purposes than that of labels for wine or spirit bottles, capable due to the nature thereof of being stored in wet environments.

SUMMARY

The aim of the present invention is therefore that of providing a method for obtaining a fibrous preparation for manufacturing a paper having significant water repellency and opacity in the dry or wet state in order to be able to use said paper for numerous purposes, said fibrous preparation having the benefit of being capable of being manufactured on a single production line.

In this regard, the present invention relates to a method for obtaining a fibrous preparation for manufacturing a paper having significant water repellency and opacity in the dry or wet state characterised in that it includes at least the following steps:

-   -   suspending fibres in water,     -   adding calcium salts to said fibres,     -   adding a source of carbonate salts in the form of an aqueous         solution,     -   stirring the resulting mixture for a time sufficient to allow         calcium carbonate particles to be precipitated,     -   adding a solution of fatty acid salts heated to a temperature         which corresponds to the micellisation temperature of said fatty         acid salts and takes into account the critical micellar         concentration of said fatty acid salts,     -   stirring the mixture thus obtained for a time sufficient to         allow the fatty acids to be absorbed at the surface of the         calcium carbonate particles and to obtain the desired fibrous         preparation.

According to an advantageous embodiment, the final step is followed by a step of adding additives and/or dyes usually used in the paper industry to the fibrous preparation obtained.

According to a conventional embodiment, the fibres are cellulose fibres.

According to an advantageous embodiment, the calcium salts have either mineral counterions or organic counterions.

The calcium salts are preferably calcium chloride.

According to an advantageous embodiment, the carbonate salts have metallic counterions or the carbonate salts can also be mineral or organic.

The carbonate salts are preferably sodium carbonate.

According to an advantageous embodiment, the dosages of calcium salts and of carbonate salts used are advantageously determined to produce, by precipitation, a mass of calcium carbonate corresponding to at most 25% of the dry matter.

Preferably, the mass of calcium carbonate produced corresponds to a value between 20 and 22% of the dry matter.

According to an advantageous embodiment, the fatty acid salts comprise between 12 and 22 carbons in their chain and their counterions can be metal or organic salts.

According to an even more advantageous embodiment, the fatty acid salts comprise 18 carbons in their chain and will be, preferably, potassium stearate.

The fatty acid salts are preferably potassium stearate.

The invention also relates to a paper having significant water repellency and opacity in the dry or wet state remarkable in that it is manufactured from the fibrous preparation receiving calcium carbonate particles produced by precipitation and bound directly at the surface and/or in the fibres thereof, and fatty acids adsorbed at the surface of the calcium carbonate particles, and obtained with the method for obtaining according to the invention.

DETAILED DESCRIPTION

The method according to the invention for obtaining a method for obtaining a fibrous preparation for manufacturing a paper having significant water repellency and opacity in the dry or wet state, is based on the principle of precipitating fillers on fibres then on modifying said fillers in order to render them less hydrophilic.

Thus, the method for obtaining a fibrous preparation includes at least the following steps:

-   -   suspending fibres, conventionally cellulose fibres, in water,     -   adding calcium salts to said fibres,     -   adding a source of carbonate salts in the form of an aqueous         solution,     -   stirring the resulting mixture for a time sufficient to allow         calcium carbonate particles to be precipitated,     -   adding a solution of fatty acid salts heated to a temperature         which corresponds to the micellisation temperature of said fatty         acid salts and takes into account the critical micellar         concentration (CMC) of said fatty acid salts,     -   stirring the mixture thus obtained for a time sufficient to         allow the fatty acids to be absorbed at the surface of the         calcium carbonate particles and to obtain the desired fibrous         preparation.

This final step can advantageously be followed by a step of adding additives and/or dyes usually used in the paper industry to the fibrous preparation obtained. Said additives and/or dyes, which are well-known to a person skilled in the art, are such as, for example, alkyl ketene dimers (AKD), cationic starch, anionic pigmentary dyes, colloidal silica, or carboxymethylcellulose, in order to give the paper manufactured from the fibrous preparation increased whiteness and opacity.

According to an advantageous embodiment, the calcium salts have either mineral counterions such as, for example, nitrate NO₃ ⁻, chloride Cl⁻, iodide I⁻, or bromide Br⁻ counterions, or organic counterions and optionally be, for example, in the form of calcium carboxylates having one to several carbons such as, for example, calcium acetate. However, preferably, the calcium salts used are calcium chloride.

Similarly, the carbonate salts in aqueous solution form have metallic counterions such as, for example, sodium Na⁺, or potassium K⁺ counterions. Moreover, the carbonate salts can also be mineral or organic such as, for example, dimethyl carbonate or ammonium carbonate. However, preferably, the carbonate salts used are sodium carbonate.

Moreover, the dosages of calcium salts and carbonate salts used are advantageously determined to produce, by precipitation, a mass of calcium carbonate corresponding to at most 25% of the dry matter and, preferably, to a value between 20 and 22%.

Furthermore, incorporating this calcium carbonate precipitation phase in the general method for manufacturing the fibrous preparation according to the invention makes it possible to ensure, when stirring the resulting mixture, the binding of the calcium carbonate particles directly at the surface and/or in the fibres, in order to increase the features of the fibrous preparation obtained. With the method for manufacturing a fibrous preparation according to the invention, it was observed that the calcium carbonate particles are, furthermore, unitary, non-agglomerated and of regular dimensions between 0.2 and 5 μm.

According to this advantageous embodiment, the fatty acid salts comprise between 12 and 22 carbons in their chain and their counterions can be metal salts (e.g.: Na⁺, K⁺) or organic salts (e.g.: NH₄ ⁺). The fatty acid salts will advantageously comprise 18 carbons in their chain and will be, preferably, potassium stearate.

Adsorbing the fatty acids at the surface of the calcium carbonate particles makes it possible to render the latter less hydrophilic and therefore significantly increase the water-repellent feature of the fibres, the fibrous preparation obtained and the paper manufactured from said fibrous preparation.

The method for obtaining according to the invention may include, if required, a step of adding fillers.

The fibrous preparation obtained with the method according to the invention is then used, without additional treatment, on a conventional paper machine for manufacturing a paper having significant water repellency and opacity in the dry or wet state. However, the paper manufactured from the fibrous preparation obtained can subsequently be coated to improve the performances thereof further or give it further functions.

Moreover, the method for obtaining according to the invention is particularly advantageous, since it does not include a fibre washing step, it can be semi-continuous or continuous and implemented on a single production line, and the white water generated thereby can be reused during the process for manufacturing paper from the fibrous preparation obtained.

Finally, it is clearly understood that the method for obtaining according to the invention makes it possible to act directly in the fibre mass of the fibrous preparation in order to obtain a specific fibrous preparation and not merely on the surface of a paper according to the prior art manufactured from a conventional fibrous preparation, which gives the paper manufactured from said specific fibrous preparation greater and more advantageous water repellency and opacity in the dry or wet state than those of the paper according to the prior art. Indeed, it is clearly understood that one of the innovative features of the method for obtaining according to the invention is based on having a step of adding a fatty acid salt solution, after precipitating the filler, said fatty acid salt solution used being heated at the micellisation temperature of said fatty acid salts. This step enables the adsorption of the micelles of fatty acids created (with the micellisation temperature) with the calcium carbonate precipitated on the fibre, which ultimately has the effect of rendering the fibres less hydrophilic.

Thus, tests according to the Cobb method demonstrated that the method for obtaining a fibrous preparation according to the invention gives the paper manufactured from this fibrous preparation a low water absorption over long periods of time. Indeed, the quantity of water absorbed by said paper after immersion for one hour only increases by 30% after 24 hours of immersion, thus proving the stabilisation over time of the water-resistance properties thereof. Moreover, it is clearly understood that with a lower water absorption, said paper has lower distortion and greater dimensional stability.

Moreover, the opacity properties of the paper manufactured from the fibrous preparation obtained with the method for obtaining according to the invention are also very good. The dry opacity of the paper is high and after immersion in water, this opacity decreases merely by close to 3% to remain stable even after 24 hours of immersion in water.

It is clearly understood that the method for obtaining according to the invention is advantageously intended to produce a fibrous preparation for manufacturing a paper for wine or spirit bottle labels. However, it is obvious that, given the high water repellency and opacity features given to the paper manufactured from the fibrous preparation obtained with the method for obtaining according to the invention, said paper may be intended for many other purposes such as, for example, the manufacture of food packaging or not.

Finally, it is obvious that the examples of methods for obtaining a fibrous preparation according to the invention described above are merely specific, in no way restrictive, illustrations of the invention. 

1-13. (canceled)
 14. A method for obtaining a fibrous preparation for manufacturing a paper having significant water repellency and opacity in the dry or wet state, comprising: suspending fibres in water, adding calcium salts to said fibres, adding a source of carbonate salts in the form of an aqueous solution, stirring the resulting mixture for a time sufficient to allow calcium carbonate particles to be precipitated, adding a solution of fatty acid salts heated to a temperature which corresponds to the micellisation temperature of said fatty acid salts and takes into account the critical micellar concentration of said fatty acid salts, stirring the mixture thus obtained for a time sufficient to allow the fatty acids to be absorbed at the surface of the calcium carbonate particles and to obtain the desired fibrous preparation.
 15. The method for obtaining according to claim 14, wherein the final step is followed by a step of adding additives and/or dyes usually used in the paper industry to the fibrous preparation obtained.
 16. The method for obtaining according to claim 14, wherein the fibres are cellulose fibres.
 17. The method for obtaining according claim 14, wherein the calcium salts have either mineral counterions or organic counterions.
 18. Method for obtaining according to claim 17, wherein the calcium salts are calcium chloride.
 19. The method for obtaining according to claim 14, wherein the carbonate salts have metallic counterions or the carbonate salts can also be mineral or organic.
 20. The method for obtaining according to claim 19, wherein the carbonate salts are sodium carbonate.
 21. The method for obtaining according to claim 14, wherein the dosages of calcium salts and of carbonate salts used are advantageously determined to produce, by precipitation, a mass of calcium carbonate corresponding to at most 25% of the dry matter.
 22. The method for obtaining according to claim 21, wherein the mass of calcium carbonate produced corresponds to a value between 20 and 22% of the dry matter.
 23. The method for obtaining according to claim 14, wherein the fatty acid salts comprise between 12 and 22 carbons in their chain and their counterions can be metal or organic salts.
 24. The method for obtaining according to claim 23, wherein the fatty acid salts comprise 18 carbons in their chain and will be, preferably, potassium stearate.
 25. The method for obtaining according to claim 24, wherein the fatty acid salts are potassium stearate.
 26. A paper having significant water repellency and opacity in the dry or wet state, wherein the paper is manufactured from the fibrous preparation receiving calcium carbonate particles produced by precipitation and bound directly at the surface and/or in the fibres thereof, and fatty acids adsorbed at the surface of the calcium carbonate particles, and obtained with the method for obtaining according to claim
 14. 27. The method for obtaining according to claim 15, wherein the fibres are cellulose fibres.
 28. The method for obtaining according claim 15, wherein the calcium salts have either mineral counterions or organic counterions.
 29. The method for obtaining according claim 16, wherein the calcium salts have either mineral counterions or organic counterions.
 30. The method for obtaining according to claim 15, wherein the carbonate salts have metallic counterions or the carbonate salts can also be mineral or organic.
 31. The method for obtaining according to claim 16, wherein the carbonate salts have metallic counterions or the carbonate salts can also be mineral or organic.
 32. The method for obtaining according to claim 17, wherein the carbonate salts have metallic counterions or the carbonate salts can also be mineral or organic.
 33. The method for obtaining according to claim 18, wherein the carbonate salts have metallic counterions or the carbonate salts can also be mineral or organic. 